Hello,
I am not able to find the bitmap image for intermediate state (CBS_MIXEDNORMAL)
That is a non-themed bitmap. If you want a themed bitmap, you have to use the DrawThemeBackground to draw it to create a bitmap.
There are two bitmaps may be used for intermediate state:
One is CBS_MIXEDNORMAL. DrawThemeBackground(theme, hdc, BP_CHECKBOX, CBS_MIXEDNORMAL, &rc, nullptr);
Another is CBS_CHECKEDDISABLED. DrawThemeBackground(theme, hdc, BP_CHECKBOX, CBS_CHECKEDDISABLED, &rc, nullptr);
Code sample as below:
HDC hdc = BeginPaint(hWnd, &ps);
HTHEME theme = OpenThemeData(nullptr, L"Button");
RECT rc = {};
rc.right = 12;
rc.bottom = 12;
DrawThemeBackground(theme, hdc, BP_CHECKBOX, CBS_MIXEDNORMAL, &rc, nullptr);
CloseThemeData(theme);
EndPaint(hWnd, &ps);
Thank you!